The present invention relates to the manufacture of magnetic and optical recording media and in particular to a method and apparatus for loading small form factor disks into sputter pallets.
In the manufacture of magnetic and optical recording media, thin films are sputtered on rigid disk substrates. The sputter process typically takes place in high volume, multiple chamber machines that employ either static or pass-through configurations. The most common form factor for which these sputter machines are configured is 95 mm. Small form factor disks, e.g., 27.4 mm disks, however, are being increasingly used. Similar to the large form factor disks, the manufacture of small form factor disks requires that thin films are sputtered onto the small form factor disk substrates. A known method for sputtering small form factor substrates is to use a sputter pallet, commonly referred to as mini-pallets, which has a large form factor, e.g., 95 mm, and holds several of the smaller substrates. With a mini-pallet, the small form factor substrates can be sputtered without reconfiguring the sputter machine, which can be expensive and time intensive.
A problem associated with the use of mini-pallets is that loading the small form factor disk substrates into the mini-pallet is difficult. The small form factor disks are positively held within the mini-pallet with springs. To load a disk into the mini-pallet, the spring is retracted, the disk placed into the mini-pallet, and then the spring is gently released to hold the disk in place without damaging the disk. Typically damage that occurs during loading includes chipping of the outside diameter edge of the substrate or cracking of the substrate. In addition, the placement of the substrates in the mini-pallet is critical. The disk must be aligned in the mini-pallet within approximately 0.001xe2x80x3. Improper loading of a disk can cause the disk to fall out during the sputter process or cause substrate damage. In addition, improper loading of the disk can lead to improper or incomplete coverage of the thin film on the surface of the disk during sputtering.
One method of loading small form factor disk substrates into mini-pallets is manual loading. Manual loading has been employed successfully for low volume manufacturing, but is not well suited for high volume production. The disadvantages of manual loading, particularly for high volume manufacturing, include low throughput, high labor cost, and often undesirable levels of substrate contamination.
Another possible method of loading small form factor disk substrates into mini-pallets is the use of pick-and-place robotics. In this method one robot would load the mini-pallet onto stand, a second robot would operate the clamping spring, and a third would pick up a small form factor substrate and place it into the mini-pallet. This system can solve the problems of labor cost, and contamination, but has a high cost due to the use of several high-precision robotic arms. The throughput can also be limited due to the multiple actions required, which could lead to the need for additional loaders and an even higher cost.
Thus, what is needed is a device for loading and unloading small form factor disk substrates into mini-pallets that is accurate, fast, reliable, and does not damage or contaminate the disk substrates.
A loading and unloading device, in accordance with the present invention, is used to load and unload a disk substrate into a pallet, where the pallet has a plurality of loading areas and a spring that extends into each of the loading areas. The spring is biased to hold a disk substrate in the loading area. The device includes a spindle that rotates the pallet, a movable arm that engages the spring to open the spring, and a disk substrate moving device. The disk substrate moving device, for example, may be an air track that provides an air cushion under the disk substrate. The disk is propelled toward the loading area by, e.g., gravity. In one embodiment, the arm engages the spring and the spindle rotates the pallet to open the spring. The disk substrate is then moved into the loading area, e.g., by increasing air pressure under the disk substrate, and the spindle then rotates in the opposite direction to close the spring thereby securing the disk substrate in the loading area. In another embodiment, the spindle does not rotate, but holds the pallet stationary, while the arm moves. For example, the arm may move laterally to open and close the spring. In another embodiment, the arm includes individual elements that engage the spring and the body of the pallet. The spring is opened or closed by the elements being moved toward or away from each other.
In another aspect of the present invention, a disk substrate is loaded into a pallet by moving the disk near the loading area of the pallet, e.g., by providing an air cushion under the disk substrate and providing a force, such as gravity, to propel the disk substrate. The arm engages the spring, which is then used to open the spring. For example, the spring may be opened by rotating the pallet while holding the arm stationary or holding the pallet stationary while moving the arm. The disk substrate is moved into the loading area, e.g., by increasing the air pressure under the disk substrate. The spring is the closed, e.g., by rotating the pallet in the opposite direction or by moving the arm in the opposite direction. The arm is then disengaged from the spring. The pallet can then be rotated to permit loading of a different disk substrate into another loading area.